MediaServer

Sleep

Puts the specified/assumed/elicited player to sleep (a long, slow, playback fade out, followed by auto power-off) after the specified time (in HH:MM:ss format).

Only the meaningful components of the duration need to be provided so there's no need to specify anything that's zero.

Invocation options (choose based on grammar-fit):

Alexa, [ open / start / launch ] MediaServer
Alexa, [ ask / tell ] MediaServer [ to / for ] …

sleep
sleep {When}
sleep in {When}
sleep this player
sleep the {Player}
sleep after {When}
sleep this player {When}
sleep the {Player} player
sleep this player in {When}
sleep the {Player} in {When}
sleep this player after {When}
sleep the {Player} after {When}
sleep the {Player} player in {When}
sleep the {Player} player after {When}